Abstract Approximately two third of cancer patients are treated with radiation, either alone or in combination with chemotherapy or surgery. Radiation can damage normal cells and this damage can lead to long-term side effects. Therefore, reduction in overall delivered radiation is beneficial to patients? quality of life and can potentially save healthcare cost. Oxygen guided radiation therapy (OGRT) is expected to reduce the high radiation dose volume by reducing the dose to well-oxygenated tumor tissue, thus preserving the structure and integrity of irradiated tissues and reducing side effects. Currently, there is no widely available non- invasive clinical or preclinical method to map oxygen partial pressure (pO2) with high accuracy. Available methods either do not provide absolute oxygen measurement deep inside the body, or are not suitable for three-dimensional oxygen map acquisition. Absence of preclinical (animal) oxygen imaging data is the major impediment in development of evidence base for advancing oxygen-based treatments into clinics. Therefore, providing research community with oxygen imaging instruments and services is the first step in achieving these goals. This Phase I SBIR grant will transition the research lab-based low frequency 25 mT (720 MHz) electron paramagnetic resonance oxygen imaging (EPROI) equipment to a commercial benchtop unit, JIVA-25. EPROI is a non-invasive oxygen imaging technique with pO2 resolution of 1-3 torr and spatial resolution of 1 mm. It has been widely applied to map hypoxia in animal solid tumors to evaluate the efficiency of anti-tumor drugs and recently, to guide tumor radiation therapy. In aim 1, we will develop acquisition and image processing software and other accessories that will make JIVA-25, a turnkey instrument, that can be operated by a technician with no prior experience in EPROI. In aim 2, we will construct an oxygen imager prototype, JIVA- 25, and develop standard operating procedure and manual. The success of this proposal will result in a commercial oxygen imager for cancer research in cancer centers, universities and pharmaceutical industry. Our long term goal is to combine this technology with clinical image guided radiation therapy (IMRT) equipment for enhanced and targeted radiation therapy.